As electronic media and other types of electronic content become increasingly popular, the need for implementing post delivery content protection and copyright management has also gained importance. In many instances, content creators wish to prevent the redistribution of content to third parties while allowing a content user to distribute the content to family members or other devices the user may own. Accordingly, content protection mechanisms have been developed to restrict redistribution and propagation of content to a limited area or distance. Such methods include using time to live (TTL) parameters in content packets, e.g., Internet Protocol (IP) packets, that limit the transmission of content to within a certain number of network segments. However, methods for circumventing the use of such TTL parameters have been developed and have weakened the level of protection provided by TTL mechanisms.
Another form of proximity restriction involves specifying a cap for the round-trip time, i.e. the amount of time required for the source device to receive a response from the sink device to an echo request. The implementation of a round trip time cap is intended to limit the distance a particular content item may be sent. However, setting a single uniform round trip time limit is often unable to anticipate and factor in the inherent delays associated with various network protocols. For example, wireless connections and wired connections often have different delays for transmitting data over the same distance. As such, a round trip time limit may prevent legitimate transfers of data over an authorized distance while allowing other transfers over distances greater than intended.
For the foregoing reasons, a system and method for enforcing proximity limitations in content distribution and propagation is needed.